Multi-layer recording medium and method for producing same

ABSTRACT

A multi-layer recording medium including a light-transmitting substrate, a first information recording layer formed on the substrate, an intermediate layer at least part of which is formed of a photo-curable resin film, and which is formed on the first information recording layer, a second information recording layer formed on a surface of the intermediate layer opposite to the surface facing the first information signal layer, and a protective layer formed on the second information signal layer. A method for producing such multi-layer recording medium is also disclosed.

BACKGROUND OF THE INVENTION

This invention relates to a multi-layer recording medium, such as amulti-layer optical disc, having plural information recording layers inwhich information signals are recorded by pits. The present inventionalso relates to a method for producing the multi-layer recording medium.

In a disc-shaped recording medium, for example, an optical disc or amagneto-optical disc, as a package medium for music or pictureinformation or recording apparatus for computers, the recent tendency istowards higher recording density of information signals. For realizingthis high density recording, there is proposed a multi-layer opticaldisc having a plurality of layered information recording layersfunctioning as a signal recording region.

Among a variety of multi-layer optical discs, there is a double-layeroptical disc having two layered information recording layers functioningas an information recording region. Such double-layer optical disc 100,shown in FIG. 1, includes a disc substrate 101 of a transparentsynthetic resin material, such as polycarbonate, on one surface of whichis formed a first information recording layer 101a by rows of pits, anda semi-transparent thin reflecting film 102 of a dielectric material,such as silicon nitride SiN, formed on the first information recordinglayer 101a. The double-layer optical disc 100 also includes anintermediate layer 103 of a transparent resin material having, on thesurface thereof opposite to the recording layer 101a, a secondinformation recording layer 103a by rows of pits, and a reflecting film104 of, for example, Al, formed on the second information recordinglayer 103a. In addition, the double-layer optical disc includes aprotective layer 105 formed on the reflective film 104.

For reading out the information signals from the double-layer opticaldisc, the focal position of a laser light radiated from an objectivelens 106 of an optical pickup device shown in FIG. 1 is changed in twosteps. That is, for reading out the information signals on the firstinformation recording layer 101a, the spot of a laser light beam L₁ islocated on the row of pits recorded on the first information recordinglayer 101a. For reading out the information signals on the secondinformation recording layer 103a, the spot of a laser light beam L₂,shown by a broken line in FIG. 1, is located on the row of pits recordedon the second information recording layer 103a. If, in such case, it isdesired to prohibit interference from being produced between theinformation recording layers 101a, 103a in the signal read-out orreproducing operation, it is necessary to set the thickness of thetransparent intermediate layer 103 between the information recordinglayers to a larger value on the order of 30 to 60 μm, for example, 40μm.

In such double-layer optical disc 100, the intermediate layer 103 isformed by any of the following two methods. The first method is tospin-coat a UV curable resin (UV resin). The second method is to applythe UV resin dropwise into a space defined between the layers 101 and105 by a spacer having a thickness corresponding to the thickness of theintermediate layer 103 for pressure bonding and curing the intermediatelayer from both side layers.

For spin-coating the UV resin for forming the intermediate layer, sincethe UV resin can be applied to a thickness only of 10 μm by one coatingoperation, the process of application followed by curing needs to berepeated e.g., four times, thus consuming much time in the production ofthe multi-layer optical disc. In addition, if spin-coating is repeated anumber of times, the UV resin is dripped or turned round to theperipheral portion thus producing thickness variations in theintermediate layer to obstruct production of the high precisionmulti-layer disc.

With the second method of dripping the UV resin into the spacer andpressure bonding and curing the resin from both side layers, it isnecessary to set the spacer in position, thus necessitating atime-consuming operation in the production of the multi-layer opticaldisc, as in the first method explained above. On the other hand, the UVresin tends to leak from the spacer thus obstructing the production ofthe high precision multi-layer disc.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide amulti-layer recording medium and a method for producing the multi-layerrecording medium in which the distance between the information recordinglayers may be sufficiently increased and the information recordinglayers may be set to uniform thicknesses.

It is another object of the present invention to provide a multi-layerrecording medium and a method for producing the multi-layer recordingmedium in which the recording medium may be produced in a shorter timewith higher precision by simplifying the formation and prohibitingvariations in thickness of the intermediate layer.

Basically, the multi-layer recording medium of the present invention isproduced by interposing a photo-curable resin film between a substratehaving formed thereon a first information recording layer and a masterdisc for transcription of a second information recording layer. Thephoto-curable resin film is pressure bonded to the substrate and themaster disc, and the master disc is then peeled off for forming theintermediate layer.

In one aspect, the present invention provides a multi-layer recordingmedium including a light-transmitting substrate, a first informationrecording layer formed on the substrate, an intermediate layer at leastpart of which is formed of a photo-curable resin film, and which isformed on the first information recording layer, a second informationrecording layer formed on a surface of the intermediate layer oppositeto the surface thereof facing the first information signal layer, and aprotective layer formed on the second information signal layer.

In another aspect, the present invention provides a method for producinga multi-layer recording medium including the steps of pressure bonding aphoto-curable resin film to a substrate having a first informationrecording layer formed thereon by a master disc for transcribing apattern of micro-sized lands and recesses of a second informationrecording layer, photo-curing the photo-curable resin film by lightirradiation, peeling off the master disc from the photo-curable resinfilm for forming an intermediate layer, forming the second informationrecording layer on the intermediate layer and forming a protective layeron the second information recording layer.

In yet another aspect, the present invention provides a method forproducing a multi-layer recording medium including the steps of pressurebonding a photo-curable resin film to a substrate having a firstinformation recording layer formed thereon, photo-curing saidphoto-curable resin film by light irradiation, interposing a liquidphoto-curable resin between the photo-curable resin film and a masterdisc for transcription of a pattern of micro-sized lands and recesses ofa second information recording layer and curing the liquid photo-curableresin by light irradiation; peeling off the master disc from the curedliquid photo-curable resin film for forming an intermediate layer,forming the second information recording layer on the intermediate layerand forming a protective layer on the second information recordinglayer.

With the above-described arrangement of the present invention, since theintermediate layer is formed between the information recording layer bythe photo-curable resin film (dry photpolymer film) or the photo-curablefilm and the photo-curable resin layer by the 2P method, theintermediate film may be of a larger and uniform thickness.

With the method for producing the multi-layer recording medium accordingto the present invention, a photo-curable resin film is interposedbetween and bonded to a semi-transparent reflective film formed on thefirst information signal layer and a master disc for transcription ofthe second information signal layer. The photo-curable resin film isthen irradiated with light and cured, after which the master disc ispeeled off for forming the intermediate layer. Thus the present methodof producing the double-layer optical disc simplifies the formation ofthe intermediate layer and suppresses its thickness fluctuations thusenabling the double-layer optical disc to be produced in a shorter timewith higher precision.

With the methods for producing the multi-layer recording mediumaccording to the present invention, since the 2P method for the liquidphoto-curable resin layer is applied after photo-curing thephoto-curable resin film, the protective sheet may be peeled off withgood peeling performance with the photo-cured resin film being bonded tothe substrate having the first information recording layer. In addition,the second micro-sized lands and recesses may be formed accurately andto high definition by the application of the 2P method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing a conventionaldouble-layer optical disc.

FIG. 2 is a schematic cross-sectional view showing an embodiment of amulti-layer recording medium according to the present invention.

FIGS. 3A to 3G illustrate the method for producing master disc forpreparation of a disc substrate for preparation of the recording mediumshown in FIG. 2.

FIGS. 4A to 4C illustrate a step for forming a substrate and a step offorming a semi-transparent reflecting film for preparation of therecording medium shown in FIG. 2.

FIGS. 5A to 5D illustrate a step for forming an intermediate layer forpreparation of the recording medium shown in FIG. 2.

FIG. 6 is a schematic cross-sectional view showing another embodiment ofa multi-layer recording medium according to the present invention.

FIG. 7 is a schematic cross-sectional view of a substrate on which isformed a first information recording layer of a multi-layer recordingmedium according to the present invention.

FIG. 8 is a schematic cross-sectional view of a transfer photo-curableresin film employed in the method for producing the multi-layerrecording medium according to the present invention.

FIGS. 9A to 9D are schematic cross-sectional view for illustrating,step-by-step, the production process for producing the multi-layerrecording medium shown in FIG. 6.

EMBODIMENTS

The first embodiment is directed to a double-layer optical disc 10having two layered information recording layers functioning as aninformation signal recording region and carrying rows of pits.

Referring to FIG. 2, the double-layer optical disc 10 includes a discsubstrate 11 of a transparent synthetic resin material, such aspolycarbonate, on the major surface of which a first informationrecording layer 11a is formed by rows of pits, and a thinsemi-transparent reflecting film 12 of a dielectric material, such assilicon nitride SiN, formed on the first information recording layer11a. The double-layer optical disc 10 also includes an intermediatelayer 13, 40 μm in thickness having, on its surface opposite to thesemi-transparent reflecting film 12, a second information recordinglayer 13a by rows of pits, and a reflecting film 14 of, for example, Al,formed on the second information recording layer 13a. In addition, thedouble-layer optical disc 10 includes a protective layer 15 formed onthe reflecting film 14.

The intermediate layer 13 is a transparent photo-curable resin film,that is, it is formed of a so-called film-forming dry photopolymer. Anexample of the film-forming dry photopolymer is one manufactured andsold by Du Pont under the trade name of "SURPHEX". This film-forming dryphotopolymer is softened at, for example, 70° C. to 80° C. and pressedagainst a mold, after which it is irradiated with UV rays so as to becured to the shape of the mold. The intermediate layer 13 of thedouble-layer optical disc 10 is generally required to be of a uniformthickness of 40 μm. Heretofore, preparation of the intermediate layer istime-consuming since the UV resin is repeatedly spin-coated to form anintermediate layer or dripped into a spacer after which it is pressurebonded in situ and cured to form the intermediate layer. The formationof the intermediate layer 13 is not time-consuming since the layer 13 isof a uniform thickness from the outset and is formed by pressure bondingthe film-forming dry photopolymer in situ.

The method for producing the double-layer optical disc 10 is nowexplained.

The method includes a step of forming the disc substrate 11 carrying thefirst information recording layer 11a, and a step of forming thesemi-transparent reflecting film 12 on the first information recordinglayer 11a of the disc substrate 11 formed by the substrate forming step.The method also includes a step of forming the intermediate layer 13 byinterposing the film-forming dry photopolymer between thesemi-transparent reflecting film 12 formed on the first informationrecording layer 11a and a master disc for transcribing the secondinformation recording layer 13a, pressure bonding the photopolymer insitu, irradiating the film-forming dry photopolymer with light forcuring the polymer and peeling off the master disc for forming theintermediate layer 13.

Before proceeding to a description of the respective steps of theproduction method, the method for producing a master disc 20 forpreparation of the disc substrate 11 and a master disc 21 forpreparation of the second information recording layer 13a will beexplained.

For preparing the master discs 20, 21, a resist 17 is coated as shown inFIG. 3B on a glass master disc 16 shown in FIG. 3A, and is irradiatedwith laser light rays as shown in FIG. 3C. The glass master disc isdeveloped as shown in FIG. 3D for forming pits 18 by molding. The masterglass disc, carrying the pits 18, is plated by electro-less plating, asshown in FIG. 3E, for forming a thin electrically conductive film 19.The glass master discs are completed by electro-plating the resultingassembly as shown in FIG. 3F. The master discs 20, 21 are peeled offfrom the glass master disc 16 as shown in FIG. 3G. The master disc 20,thus prepared, is employed for molding a substrate.

First, the master disc 20, functioning as a stamper, is set in a moldingunit 22, into which a polycarbonate resin material, melted at a hightemperature, is introduced, as shown in FIG. 4A. The resin material iscompression-molded for molding the disc substrate 11, to which the firstinformation recording layer 11a has been transcribed, as shown in FIG.4B.

The semi-transparent thin reflective film 12, formed of, for example,silicon nitride SiN, is formed by sputtering on the first informationrecording layer 11a, as shown in FIG. 4C. This semi-transparent thinreflective film 12 reflects 20 to 40% of the laser light, with awavelength of 632 nm, generated by an He--Ne laser, while transmitting50 to 80% of the same laser light.

A film-forming dry photopolymer 13' is then interposed between thesemi-transparent reflective film 12 formed on the first informationrecording layer 11a and the master disc 21 designed for transcription ofthe second information recording layer 13a. The film-forming dryphotopolymer 13' is of a uniform thickness of, for example, 40 μm. Thisfilm-forming dry photopolymer 13' is inserted as shown in FIG. 5A afterbeing heated to, for example, 70° C. The film-forming dry photopolymer13', interposed between the semi-transparent reflective film 12 and themaster disc 21, has its both surfaces pressed between the master disc 21and the semi-transparent film 12 of the disc substrate 11 by pressurerolls 23a and 23b, as shown in FIG. 5B. The film-forming dryphotopolymer 13', having its both surfaces pressure-bonded to the masterdisc 21 and the semi-transparent film 12 by rotation of the pressurerolls 23a and 23b, is cured by irradiation of UV rays from a UV lamp 24,as shown in FIG. 5C, to form the intermediate layer 13. After formationof the intermediate layer 13, the master disc 21 is peeled off, as shownin FIG. 5D. After peeling of the master disc 21, the second informationrecording layer 13a has been transcribed on the intermediate layer 13.

On the second information recording layer 13a, the reflective film 14 ofaluminum Al, reflecting 80% of the laser light from the He--Ne laser, asshown in FIG. 2, is formed by sputtering. On the reflective film 14 isformed the protective film 15 as shown in FIG. 2.

As described above, the double-layer optical disc 10 is formed byforming the intermediate layer 13 by interposing the film-forming dryphotopolymer 13' of a uniform thickness between the semi-transparentreflective film 12 of the disc substrate 11 and the master disc 21 andpressure bonding the photopolymer 13' to the semi-transparent reflectivefilm 12 of the disc substrate 11 and to the master disc 21 by thepressure rolls 23a, 23b, as shown in FIGS. 5A to 5D. Thus the presentmethod of producing the double-layer optical disc 10 simplifies theformation of the intermediate layer 13 and suppresses its thicknessfluctuations thus enabling the double-layer optical disc 10 to beproduced in a shorter time with higher precision.

Although the present embodiment is directed to the double-layer opticaldisc 10, an optical disc of three or more layers may be easily producedby repeating the transfer of the semi-transparent reflective film 12 andthe film-forming dry photopolymer 13' a desired number of times.

FIG. 6 shows, in a schematic cross-section, a modification of thepresent invention in which first and second information recording layers41, 42, respectively carrying first and second micro-sized lands andrecesses 51 and 52, such as recording pits or tracking pre-grooves forinformation data, are layered with the interposition of a transparentintermediate film 63 in-between. The transparent intermediate film 63 isformed by a transparent transferable photo-curable resin film 90 and acured (hardened) layer of liquid photo-curable resin 33. The transparenttransferable photo-curable resin film 90 is formed so as to fillrecessed portions of the first micro-sized lands and recesses 51.

In this case, a transparent substrate 31, having formed on one of itsmajor surfaces first micro-sized lands and recesses 51, such asrecording pits for the data information and a pregroove for tracking, isprovided, as shown in FIG. 7. This transparent substrate 31 is formed byinjection molding of, for example, polycarbonate (PC). On thesemicro-sized lands and recesses 51 is deposited a semi-transparent film43 of, for example, SiN.

The transparent transferable photo-curable resin film 90, that is afilm-forming dry photopolymer manufactured by Du Pont under the tradename of "SURPHEX", is provided, as shown in FIG. 8. This film-formingdry photopolymer 90 has both its surfaces coated with peelableprotective sheets 91, 92. Referring to FIG. 9A, one of the protectivesheets 91 is now peeled to expose a surface of the film 90, which isthen abutted against the first information recording layer 41 of thesubstrate 31. The resulting assembly is introduced into a space betweenpressure rolls 93 and 94 and softened at a temperature of, for example,70° C. to 80° C. for pressure bonding the film 90 to the substrate 31.

With the remaining protective sheet 92 deposited on the film 90, UV raysare radiated from the side of the transparent substrate 31 for curingthe transparent transferable photo-curable resin film, that is thefilm-forming dry photopolymer 90, as shown in FIG. 9B.

The protective sheet 92 of the film 90 is then peeled off, as shown inFIG. 9C. Since the film 90 has been cured by exposure to light, theprotective sheet 92 is peeled off satisfactorily, with the film 90remaining tightly bonded to the first information recording layer 41 ofthe substrate 31.

The second information recording layer 42 is formed by the 2P method onthe substrate 31 having a planar surface by the transparent transferablephoto-curable resin film 90 buried in the first micro-sized lands andrecesses 51. To this end, the side of the substrate 31 having the film90 is abutted against and bonded under pressure to a stamper 38 via aliquid photo-curable resin 33 such as UV curable resin manufactured byNIPPON GOSEI GUM CO., LTD. under the trade name of R6021, so that thepattern of micro-sized lands and recesses of the stamper 38 istranscribed to the liquid photo-curable resin 33 for forming the secondmicro-sized lands and recesses 52 therein as shown in the schematiccross-sectional view of FIG. 9D. The UV rays are irradiated from theside of the substrate 31 for curing the liquid photo-curable resin 33.

The stamper 38 is then peeled off. This transcribes the pattern of themicro-sized lands and recesses on the stamper 38 to form the secondmicro-sized lands and recesses 52. Referring to FIG. 6, there is formedon the surface of the substrate 31 having the second micro-sized landsand recesses 52 a reflective film 44, such as an Al vapor-depositedfilm, for forming the second information recording layer 32. Aprotective film 44 is deposited on the second information recordinglayer 32. In this manner, the first and second information recordinglayers 41 and 42 are layered, while the transparent intermediate film 63is formed by cured layers of the transparent transferable photo-curableresin film 90 and the liquid photo-curable resin 33.

The reflective film 44 of, for example, Al, is then formed on the secondmicro-sized lands and recesses 52, and a protective film of, forexample, UV curable resin, is formed thereon for producing the ultimatedouble-layer optical disc, that is a multi-layer optical recordingmedium.

Since the multi-layer optical recording medium according to the presentinvention is produced by layering the transparent transferablephoto-curable resin film 90 and the liquid photo-curable resin 33,produced by the 2P method, the distance between the first and secondinformation recording layers 41 and 42 may be set to a larger value of,for example, 30 to 60 μm, such as 40 μm. Basically, the transparentintermediate film 63 may be set to a uniform thickness since thetransparent transferable photo-curable resin film 90 employed has apre-set constant thickness.

The second micro-sized lands and recesses 52 may be reliably andaccurately formed by applying the 2P method in forming the secondinformation recording layer 42, so that a multi-layer, hereindouble-layer optical recording medium, having superior opticalcharacteristics, may be produced.

In the above-described embodiments, the optical disc having twoinformation recording layers is produced. However, the present inventionmay also be applied to a multi-layer optical recording medium havingthree or more information recording layers, or to a multi-layer opticalrecording medium having plural information recording layers, such asphotomagnetic recording layers or phase transition recording layershaving micro-sized lands and recesses, other than the optical disc.

Also, in the above-described embodiments, the first micro-sized landsand recesses 51 of the first information recording layer 41 are formedby injection molding simultaneously with the molding of the substrate 1.However, the first micro-sized lands and recesses 51 may also be formedby, for example, the 2P method. In the above-described method of thepresent invention, irradiation of the liquid photo-curable resin 33 withphoto-curing light is through the substrate 31 and the as-curedtransparent transferable photo-curable resin film 90, the substrate 31is formed by a transparent substrate having high transmittance withrespect to this wavelength light, for example, UV rays, such as thelight having the wavelength of 365 nm (i-rays). The transparenttransferable photo-curable resin film 90 may be designed so that itsspectral properties are changed after curing from those prior to curingsuch that the as-cured polymer exhibits high transmittance with respectto UV rays. An insulator may also be added which will raisephotosensitivity with respect to the light transmitted through thetransparent transferable photo-curable resin film.

In the multi-layer recording medium of the above-described embodiments,the substrate 31 and the transparent intermediate film 63 exhibits hightransmittance with respect to the semiconductor laser light used forrecording or reproduction of the information signals for the recordingmedium, while the semi-transparent film 43 has optical properties ofpartially reflecting and partially transmitting the similar light.

The foregoing description has been made with reference to a ROM typedouble-layer optical disc in which the first and second informationrecording layers, each having micro-sized lands and recesses, such asinformation data recording pits or tracking pre-grooves, are layeredwith the interposition of the transparent intermediate film in-between.The present invention, however, is not limited to the optical disc. Onthe contrary, the present invention may be applied to a variety ofoptical recording media, such as magneto-optical discs, phase-transitionoptical discs, or card- or sheet-shaped recording media, other than theoptical disc, in which two or more information recording layers havingmicro-sized lands and recesses are layered with the interposition of thetransparent intermediate film.

What is claimed is:
 1. A multi-layer recording medium, comprising:alight-transmitting substrate; a first information recording layer formedon said substrate; an intermediate layer at least part of which isformed of a dry photo-curable resin film, and which is formed on saidfirst information recording layer; a second information recording layerformed on a surface of said intermediate layer opposite to the surfacethereof facing said first information signal layer; and a protectivelayer formed on said second information signal layer.
 2. The multi-layerrecording medium as claimed in claim 1, wherein said first informationrecording layer has a pattern of micro-sized lands and recesses which isburied in said dry photo-curable resin film.
 3. The multi-layerrecording medium as claimed in claim 1, wherein said intermediate filmis formed only by the dry photo-curable resin film and wherein a patternof micro-sized lands and recesses constituting the second informationrecording layer is formed on a surface of dry said photo-curable resinfilm opposite to said information recording layer.
 4. The multi-layerrecording medium as claimed in claim 1, wherein said intermediate filmis formed by the dry photo-curable resin film and a liquid photo-curableresin layer provided on the side of the first information recordinglayer and on the side of the second information recording layer,respectively.
 5. The multi-layer recording medium as claimed in claim 4,wherein the pattern of micro-sized lands and recesses constituting thesecond information recording layer is formed on said liquidphoto-curable resin layer.
 6. The multi-layer recording medium asclaimed in claim 1, wherein said multi-layer recording medium is adouble-layer optical disc wherein said first and second informationrecording layers function as an information signal recording region andcarry rows of pits.
 7. The multi-layer recording medium as claimed inclaim 1, wherein said light-transmitting substrate comprises atransparent synthetic resin on the major surface of which the firstinformation recording layer is formed by rows of pits.
 8. Themulti-layer recording medium as claimed in claim 6, further including athin semi-transparent reflecting film of a dielectric material formed onthe first information recording layer.
 9. The multi-layer recordingmedium as claimed in claim 1, wherein the intermediate layer has athickness of about 40 micrometers and said dry photo-curable resin filmis a film-forming dry photopolymer.
 10. The multi-layer recording mediumas claimed in claim 8, wherein said intermediate layer is of a uniformthickness from the outset and is formed by pressure bonding thefilm-forming dry photopolymer in situ.
 11. A multi-layer recordingmedium, comprising:a substrate of a transparent synthetic resinmaterial; a first information recording layer formed by rows of pits onthe major surface of said substrate; a thin semi-transparent reflectingfilm of a dielectric material formed on the first information recordinglayer; an intermediate layer having, on its surface opposite to thesemi-transparent reflecting film, a second information recording layerby rows of pits; and a protective layer on said reflecting film, whereinsaid intermediate layer is a transparent photo-curable resin film formedof a film-forming dry photopolymer having a uniform thickness from theoutset without requiring spin-coating a plurality of layers to reachsaid uniform thickness or dripping resin into a spacer, and formed bypressure bonding the film-forming dry photopolymer in situ.
 12. Themulti-layer recording medium as set form in claim 11 wherein saiduniform thickness is about 40 micrometers.
 13. The multi-layer recordingmedium as set forth in claim 11, wherein the multi-layer recordingmedium is a double-layer optical disc wherein said first and said secondinformation recording layers function as an information signal recordingregion, and said substrate is a disc substrate.
 14. The multi-layerrecording medium as claimed in claim 11, wherein said first informationrecording layer has a pattern of micro-sized lands and recesses which isburied in said photo-curable resin film.
 15. The multi-layer recordingmedium as claimed in claim 11, wherein said intermediate film is formedonly by dry photo-curable resin film and wherein a pattern ofmicro-sized lands and recesses constituting the second informationrecording layer is formed on a surface of said photo-curable resin filmopposite to said information recording layer.
 16. The multi-layerrecording medium as claimed in claim 11, wherein said intermediate filmis formed by a photo-curable resin film and dry liquid photo-curableresin layer provided on the side of the first information recordinglayer and on the side of the second information recording layer,respectively.
 17. The multi-layer recording medium as claimed in claim16, wherein the pattern of micro-sized lands and recesses constitutingthe second information recording layer is formed on said liquidphoto-curable resin layer.